796 



SCIENCE. 



[N. S. Vol. XVI. No. 411. 



As far as beards and velvet chaff are con- 

 oerned, it is seen that these hybrids obeyed 

 Mendel's law in a very satisfactory manner. 



In all the fourteen crosses one parent had 

 the short head characteristic of the club group 

 of wheats, while the other had the common 

 long form of head. In general the first gen- 

 eration of hybrids were intermediate between 

 the parents in this respect. In the second 

 generation the progeny of each plant of the 

 previous generation presented every gradation 

 between the parents, presenting a continuous 

 series, which, in most cases, extended beyond 

 both parents. Correns mentions such a series 

 in some of his hybrids, and offers the explana- 

 tion that in some individuals the character of 

 the male parent is dominant, in others, the 

 corresponding character of the female parent, 

 while in the remaining individuals there are 

 all degrees of variation as regards the domi- 

 nance of this pair of characters. I shall not 

 take issiie with him, but will offer a different 

 hypothesis to explain the facts. According 

 to Mendel's theory, when a pair of characters 

 separate, they do so completely. For in- 

 stance, if a hybrid has in it both the bearded 

 and the beardless character, on the formation 

 of pollen and ovules, the one character passes 

 entire into some of the pollen grains and 

 ovules, the other passes entire into the others. 

 This would indicate that the character of 

 beard-producing is due to something which 

 retains its individuality during the process 

 of germ cell formation; and so for all charac- 

 ters that obey Mendel's law. Is it not pos- 

 sible, however, that the protoplasmic basis of 

 some characters, instead of passing entire into 

 the germ cells, itself splits up in all possible 

 proportions, so that we may find pollen grains 

 and ovules possessing all degrees of the tend- 

 ency to develop a certain character. This 

 hypothesis would explain the behavior of my 

 hybrids with reference both to length of heads 

 and color of chaff.* 



Eeeurring now to the form in which I first 

 stated the law governing the transmission of 

 parent characters in hybrid offspring, I would 



* Since the above was Avritten I find that Pro- 

 fessor Bateson has proposed the same hypothesis. 

 See Rep. Evol. Com., Royal Society. 



modify the second clause of the law to read 

 as follows : With reference to some of the 

 parent characters, the second generation of 

 a hybrid presents all possible combinations of 

 the characters of the two parents; with refer- 

 ence to other characters, the hybrids (second 

 generation) show every possible gradation be- 

 tween the characters of the two parents. 



The first clause here applies . to character 

 pairs that separate in the manner called for 

 by Mendel's, theory; the second clause applies 

 to characters which separate in all possible 

 proportions. I am at present unable to pre- 

 sent data for the third and later generations 

 of my hybrids, since the work I inaugurated 

 at Pullman, Washington, is now in other 

 hands, but I hope to be able to do so in the 

 near future. W. J. Spillman. 



U. S. Depabtment of Agricuxtuee. 



i'OTES ON INORGANIC CHEMISTRY. 

 ' The Chemical Composition of Insecticides 

 and Fungicides ' is the title of Bulletin No. 

 68 of the Bureau of Chemistry, U. S. Depart- 

 ment of Agriculture, just issued by the gov- 

 ernment. Its author is J. K. Haywood, chief 

 of the Insecticide and Agricultural Water 

 Laboratory. The investigation of the subject 

 of the report was undertaken with the coopera- 

 tion of the Division of Entomology. Through 

 the state experiment stations and special 

 agents, samples were procured from different 

 sections of the country of the various insecti- 

 cides and fungicides on the market, and the 

 report embodies the analyses of some one hun- 

 dred and fifty. Of these nearly one third 

 were Paris green, and a dozen more were Lon- 

 don purple. Most of these samples were ex- 

 cellent in quality, few only showing an excess 

 of soluble arsenious oxid and still fewer re- 

 vealing any suspicion of adulteration. Of the 

 insecticides sold under fancy names and con- 

 taining arsenic not as much can be said. 

 Some of them are excellent, but many reveal 

 a large proportion of inert matter. If the 

 price were correspondingly low this would not 

 be an objection, but where a mixture of gyp- 

 sum with less than two per cent, of Paris 

 green is sold at five cents per pound it is an 

 imposition on the purchaser. The soaps, hel- 



